/Engine/Plugins/Runtime/XRBase/Source/XRBase/Public/XRRenderTargetManager.h
Optional method called when the ViewportWidget is not null
virtual void UpdateViewportWidget ( bool bUseSeparateRenderTarget, const class [FViewport](API\Runtime\Engine\FViewport) & Viewport, class [SViewport](API\Runtime\Slate\Widgets\SViewport) * ViewportWidget )